Controlling an agent, your mission is to enter an embassy, maneuver throughout each of the embassy's first four floors using the stairs, or the elevator, search the rooms behind a door on each floor for items, eventually finding and obtaining stolen secret plans from the embassy's vault, and escaping as quickly as possible, while avoiding the embassy guards.
Scattered throughout the rooms behind the doors in the embassy (rooms are concealed from view until your spy enters them), are various items to aid your agent. The key, allowing your agent past the locked door on the fifth floor, the combination, which opens the vault door, the I.D. card, that bypasses the security system to the vault door preventing electrocution, and the disguise, which gets you past the sentry without being detected are required to complete the mission. The running shoes, which lets your agent run faster, the map, which reveals the contents of all of the rooms in the embassy, the wrench, which breaks the elevator (and traps any enemy guards inside), and the umbrella, allowing your spy to parachute off the roof of the embassy safely, are not required to complete the mission, but will make completing the mission easier.
You earn points for picking up the items, for trapping guards in the elevator using the wrench, and bonus points for opening the vault, getting the secret plans, and jumping off the embassy roof with the umbrella before the timer at the top of the screen runs out. You lose an agent by being caught by the guards, falling down the elevator shaft, letting the sentry at the safe see you without the disguise, or not having the I.D. card to bypass the security system's electrified floor. You will also lose an agent if you jump off the building with the umbrella without getting the plans, after breaking the elevator; you will be unable to enter the embassy, the timer will rapidly count down to zero, and you lose your agent. A secret storm weapon also exists in the game that can move quickly and kill your agent with deadly speed.
When you succeed in a mission, you start a new mission, which is more difficult, and has more difficult guards.